by Jim Barnes
As production runs shorten and part geometries get more complex, five axis machine tools are starting to go mainstream. The efficiency and ROI possible with what once were considered specialty machines are making an impact on many shop owners.
“We’re seeing more interest coming from outside the traditional markets for five axis machines,” notes Alan Hollatz, proposal engineer, Makino Inc. He cites interest in the auto industry, for example. “Five years ago, they would not even have thought about it.”
You don’t need to make blisks to profit from five axes. “Less than five per cent of the people who have five axis machine tools actually do simultaneous, five axis machining,” explains Jim Endsley, machining center product specialist, Okuma America Corp., Charlotte, NC. “The rest of them do what we call multi-tasking,” where some operations are performed sequentially.
Many potential new users look at five axis technology with caution. New users can expect a learning curve with five axis, and it’s important to minimize errors during that time, says Nitin Chaphalkar, team leader, Machining Technology Laboratory, DMG/Mori Seiki USA. (In Canada, the two companies operate separately. DMG Canada is based in Mississauga, ON, and Ellison Technologies, Mississauga, ON, is the Canadian distributor for Mori Seiki machines.) It’s a niche area. Finding the right operator and providing training is crucial, he adds.
“There are customers who acquire five axis machines and don’t really understand what they’ve gotten into, so they don’t really take full advantage of what they have,” says Hollatz. “The fifth axis adds some complexity and you have to consider things that you may not have needed to consider before. Sometimes, people overlook that.”
Non-simultaneous five axis machining has been described as five-faced or five-sided machining, universal machining, multi-tasking and so on. “To me, five-sided machining is being able to grab a part, hold it by one side, and have access to the other five size of the cube. Theoretically, you can produce a part in two operations,” says Hollatz.
It might be even faster than that. “On a universal machining centre, if the part has a blind side – and 60 per cent of the parts being made today do – you can do that part in one setup. You handle it a maximum of two times,” says Endsley. Contrast that with a typical horizontal machining center, where you might handle a part up to six times before it’s finished, he says.
“The setup time is maybe 15 per cent of what it would be with a typical horizontal machining center,” says Endsley. That reduces the need for labour. “Every time a human being touches a part, it adds cost to the part, and that cost cannot be recouped.”
That also lowers the risk of damage – possibly losing a tool reference from one face to another due to an error in fixturing, explains Vince D’Alessio, executive vice president, Elliott Matsuura Canada, Oakville, ON.
Programming in five axes can make some new users a little nervous. Powerful CAD/CAM software can make the task a little less intimidating, but it’s important to make sure you have the right post-processor.
“A lot of people invest in the software and don’t consider the post… There has to be a very close tie between the programming software and the machine,” says Chaphalkar. “The programming software has to give the right point distribution and the machine has to be able to execute that point distribution.”
The software may also be able to check programs for machine-specific errors. “Everyone’s coming up with their own version of collision avoidance,” says D’Alessio. This software takes data on the design, the tooling, the fixturing and the machine, and tells you whether the program is viable or not, he explains.
Your tooling strategy may also need a re-think. One issue is the size of the tool magazine. If you run short batches with a high mix of parts, keeping all the tools you need in the machine is essential to achieving high spindle utilization.
“I see large tool magazines being used to eliminate setups,” says Endsley. That eliminates downtime due to missing tools, for example. Redundant tooling will help you avoid stopping the machine unnecessarily to change inserts.
You should consider quick-change tooling in the interests of productivity, and shrink-fit tooling for rigidity and more tool overhang, says Chaphalkar.
You may also be able to shorten up your tooling for more aggressive cuts and simplify your fixturing. “Those are two typical benefits of five axis,” says Hollatz. “Both of them allow you to be more efficient in your cutting.”
Fixturing is another consideration. “The way you hold a part on a five axis machine is probably different than the way you’ve been doing it on a horizontal or a vertical,” explains D’Alessio. “Some customers buy a five axis machine and they want to put five parts on a pallet. You can do that, but you may lose the ability to go to all five faces.”
Multiple pallets can extend your options. “Most of our horizontal machining centers are two-pallet machines,” explains Hollatz. “It’s not uncommon to put a fifth axis on one pallet. The second pallet has a tombstone or a fixture on it. You do that first operation on the tombstone in a three or 3-1/2 axis process. On the second pallet, you take the part off the tombstone and put it in the fifth axis and finish it completely in the second operation,” he says.
A profitable investment in five axis machining depends on planning and systems integration. “You don’t just buy a machine and push the ‘go’ button. There’s more infrastructure, more of a support network that goes with five axis,” says Hollatz. “A lot of peripheral issues may be more significant than they are with three- or four-axis machines.”
“It requires organizing your programming and organizing the shop to make sure that when you do a setup, all the pieces are there to keep that setup time minimal… It’s not necessarily five axis, it’s the whole package. It’s inspection, its programming, it’s tooling, it’s fixturing, it’s pallets – it’s everything,” says D’Alessio.
“Some people think that five axis machining is going to move their spindle utilization from 40 or 45 per cent to 85 or 90 per cent, all by itself,” he says. Not true, but “If you have all your jobs set up and all the tools in the magazine and the programs already written, then it’s just a matter of the operator putting new material in the fixture for each job. That gets your spindle utilization up to 85 to 90 per cent.”
Five years ago, owners tended to look at a five-year ROI on a machine. “Now, sometimes, it’s 10 months. The average today is probably about 18,” says Endsley. Tracking your costs and keeping the spindle turning is only way to achieve that.
“We often see a certain caution in customers who are just getting their first five axis machines, which is good,” says Hollatz. “But some people think, ‘I’m going to treat it like the three-axis.’ On some geometries, that is the right way to do it,” but usually an opportunity is being missed.
“If I can make all my parts by processing one face in one operation, and then do everything else in the second operation, that’s about as efficient as I’m ever going to be. A five axis machine allows you to do that,” says Hollatz.
The machines can give you capabilities your competitors don’t have. “As a businessman, you’ve differentiated yourself and your throughput is higher,” says Endsley.
Jim Barnes is a Toronto-based freelance writer with more than thirty years of experience in business journalism.